I'm a fan of the Quality stuff and have written a bit on my websites about their characters as well as my own research into the issues of copyrights concerning them and other GA companies.
However, if you are writing a book, I'd suggest spending time doing the research yourself and interviewing the people at the Library of Congress concerning issues and procedures of copyrights (would take only about a day) OR paying them or an intellectual properties lawyer to research a few titles to see if it jibes with what I and others contend, that the vast majority of Quality books are pd. Only some of the post 1950 Quality titles ever had their copyrights renewed, nor is there a record of transfer of any copyrights to DC (although they renewed some of those 1950s issues). I'm reasonably confident of my own research, but I'm not a recognized authority.